The present invention relates to preventing and/or removing condensation from smooth surfaces, and more particularly, to a system for automatically preventing and/or removing condensation from at least a portion of a glass or mirrored surface.
Many people are familiar with the problems associated with using a bathroom mirror shortly after taking a shower or bath, or while the shower or bath is otherwise on. The moisture in the air from the hot water of the shower or bath condenses on the mirror surface and impairs visibility. Although many residential bathrooms have an exhaust fan that accelerates the removal of moisture from the bathroom, most bathroom fans require an appreciable amount of time before condensation on the mirror surface is dissipated.
U.S. Pat. No. 4,956,542 to Prosser discloses a mirror defogger assembly that uses a heating element to prevent condensation from forming on the surface of a mirror. The mirror defogger assembly includes a humidistat, a control module/transformer, and a heating element that is attached to the surface of the mirror. The humidistat sends an electronic signal to the control module/transformer when the humidity level reaches a predetermined point. The electronic signal, when received by the control module/transformer, activates the heating element, thereby warning the mirror surface and preventing condensation. Although mirror defogging systems that incorporate a heating element are known in the art, such systems are limited due to cost, reliability, as well as a number of other factors. For example, in the mirror defogger assembly of Prosser, the use of a transformer to convert household AC power to a level suitable for use with the heating element adds both cost and bulk to the assembly.
The present invention provides a reliable and inexpensive condensation prevention and/or removal system that can be attached to any surface upon which condensation may form. Advantageously, embodiments of the present invention can be directly connected to standard household wiring without the use of special power supplies or transformers. Moreover, embodiments of the present invention automatically turn on and off to control condensation formation based on the humidity of the ambient environment and without any user intervention. This automatic operation keeps the condensation prevention and/or removal system from being left in an on condition, thereby enhancing safety and reducing operating costs.
According to one embodiment of the present invention, a condensation control system is provided having a first terminal that is adapted to be directly connected to an AC power source and a second terminal. The condensation control system includes a heating element, a power regulation device having a trigger, a voltage divider having an output, and a humidity sensor. The heating element is electrically coupled in series with the power regulation device between the first and second terminals. The voltage divider is electrically coupled in series between the first and second terminals and in parallel with the heating element and the power regulation device. The humidity sensor is electrically coupled between the output of the voltage divider and the trigger of the power regulation device. The humidity sensor senses an amount of humidity and triggers the power regulation device to activate the heating element when the amount of humidity sensed by the humidity sensor is greater than a predetermined humidity threshold set point.
According to another embodiment of the present invention, a condensation control system is provided having a first terminal that is adapted to be directly connected to an AC power source and a second terminal. The condensation control system includes a heating element, a power regulation device having a trigger, first, second, and third resistors, and a humidity sensor. The heating element is electrically coupled in series with the power regulation device between the first and second terminals. The first resistor and the second resistor are electrically coupled in series between the first and second terminals and in parallel with the heating element and the power regulation device. The third resistor is electrically coupled between the trigger of the power regulation device and the second terminal. The humidity sensor is electrically coupled in series between the first resistor and the second resistor. The humidity sensor has a first terminal that is electrically coupled to the first resistor and a second terminal that is electrically coupled to the second resistor and the trigger of the power regulation device. The humidity sensor senses an amount of humidity and triggers the power regulation device to activate the heating element when the amount of humidity sensed by the humidity sensor is greater than a predetermined humidity threshold set point.
According to further aspects of the present invention, the power regulation device may include a triac, a thyristor, or other types of SCRs. Moreover, embodiments of the present invention may be used with different types of humidity sensors, such as variable resistance humidity sensors and variable capacitance humidity sensors, and may be used to activate the heating element to remove or prevent condensation over one half of an AC cycle, or over the full AC cycle.